ALgebra
posted by mike .
the difference between two numbers is 7. the larger number is 9 less than 3 times the smaller. find the numbers

Let a = smaller and b = larger number.
a = b  7
3a  9 = b
Substitute b7 for a in the second equation and solve for b. Put that value in the first equation to find a. To Check, put both values into the second equation.